Seaside town with large dump (5)
I believe the answer is:
hovel
'dump' is the definition.
(I've seen this before)
'seaside town with large' is the wordplay.
'seaside town' becomes 'hove' (I have seen 'coastal town' mean 'hove' so perhaps 'town' could also mean 'hove'. I am not sure about the 'seaside' bit.).
'with' says to put letters next to each other.
'large' becomes 'L' (eg in clothes sizes).
'hove'+'l'='HOVEL'
Can you help me to learn more?
(Other definitions for hovel that I've seen before include "Dimly illuminated" , "Ramshackle dwelling" , "Degraded house" , "Squalid dwelling" , "bad housing" .)